Enhanced Field Emission Characteristics of a 3D Hierarchical HfO ₂ ‐ZnO Heteroarchitecture

Three dimensional (3D) HfO 2 ‐ZnO heteroarchitecture comprised of thin coating of HfO 2 on self assembled 3D ZnO urchins with pointed apex has been synthesized using hydrothermal route followed by Pulsed Laser Deposition (PLD). The as‐synthesized HfO 2 ‐ZnO heteroarchitecture was characterized using XRD, SEM, EDS, and (HR) TEM, in order to reveal its structural, morphological, and chemical properties. The HfO 2 ‐ZnO heteroarchitecture emitter exhibits superior field emission (FE) behaviour in contrast to the pristine ZnO urchins, demonstrated by delivery of high emission current density of ∼ 885 μA/cm 2 at an applied field of ∼ 3.35 V/μm, against ∼383 μA/cm 2 at an applied field of ∼ 4.32 V/μm for the pristine ZnO urchins emitter. Interestingly, the HfO 2 ‐ZnO heteroarchitecture emitter exhibits excellent emission current stability characterized with fewer fluctuations, owing to very good ion‐bombardment resistance offered by the HfO 2 coating. Furthermore, the heteroarchitecture thus obtained facilitates tailoring of the morphology with high aspect ratio and modulation of electronic properties as well, thereby enhancing the FE behaviour.Despite HfO 2 being wide band gap and high‐k material, the HfO 2 ‐ZnO heteroarchitecture exhibits potential as promising candidate for fabrication of high current density cold cathode